Generally, men often put on several pairs of socks when putting on shoes in order to preserve the warmness in the cold winter or to prevent blister formation on the feet during an exercise including the mountain climbing and jogging.
Wearing several pairs of socks is troublesome and furthermore poor ventilation is apt to cause athlete's foot or bad smell after long hours. Incidentally, several sewed lines are overlapped at about the same positions, because the finishing suturing takes place at the toe parts of socks for most ordinary socks. As the result, the uppers of running shoes come in contact with the above-described suturing, when such shoes are put on during an exercise, for example, to increase the pressure on the toes. In the cases of severe exercise, the skins on the toe areas of the athletes are often peeled off due to the friction between the suturing of socks and the skins.
To remove such an inconvenience, in recent years, double socks which have the effect of two individual socks were developed and placed on the market. As a representative example of the double socks on the market, there are the kinds of double socks, which are formed by the steps of knitting two sheets of socks separately, putting one into the other sock and finally suturing the two socks either at the ankle positions or at other two or three positions. While this kinds of socks have the general advantage of the double socks, they have some flaws. That is, in case the toe parts of the inner and outer socks are not firmly joined by suturing, every movement of feet during walking or exercising does not lead to a synchronized movement of the inner and outer socks, or in some cases the inner socks get stuck between the toes, deteriorating the wearing feeling. In addition, the working procedure of inserting inner socks into outer socks and aligning the two sheets of socks with regard to every part of socks is complex and time-consuming to raise manhours or increase the manufacturing cost, let alone the unsanitary state of the finished product in use due to poor ventilation.
Another exemplar socks are produced by knitting two pieces of socks in succession, as in the ordinary case, putting the inner sock into the outer sock and subjecting the resulting one to the finishing step of suturing the toe parts of the two socks together in a manual or mechanical way. In this method, the suturing step is conducted at the outside of the outer sock and therefore there are chances of suturing only the toe part of the outer sock, leaving the toe part of the inner sock unsutured due to the mistake of the worker, causing the high rate of failed productions.
Furthermore, the sutured portions become rugged and thick, besides the difficulty of suturing, because the two junctures, i.e. one for the inner sock and one for the outer sock, should be sutured together simultaneously. Additionally, in the case of this type of socks, the thick sutured portions imposed the suppression on the toe area of feet, as in the case of wearing two separate pairs of socks, making wearing feeling uncomfortable and the appearance of the product also was untidy.